Praxis
Posted: Fri Jun 19, 2009 3:50 am
I intend for this thread to be a catch-all for all things related to my install. Theoretically this thread will help anybody that chooses to follow behind me. However, I fully realize that, due to the rarity of the system and fact it's discontinued, the chances of another install on a Legacy is almost nil. That said, Mods may move this to Build Journals or Pictures and Multimedia if they see fit.
What is Praxis?
Praxis is an experiment by Bridgestone/Firestone to enter the performance suspension market utilizing Firestones extensive experience with air springs. Even though the product is discontinued the website is still live. It can explain the basics better than I can: http://www.praxissystems.com/ In my research I discovered that most of the system is very similier to, and uses parts from, other Firestone "air-ride" systems.
The system can be considered a failure based on sales and an early retail retirement. In my opinion it failed because of price ($3500 new) and unreasonable expectations on the part of prospective customers.
Why am I installing it?
Because I believe it was a good effort to produce a versatile "all purpose" suspension that, IMHO, matches our Subaru's "go anywhere, do anything" pesonality. Particularly a turbo Subaru.
What are the pros?
Automatic, in-car, ride height AND spring rate adjustment. 12 position adjustable, inverted H&R struts. Automatic load leveling and corner weighting. Reduces side load on the strut. Reduces unsprung weight. It's really cool.
What are the cons?
Stuts are adjusted traditionally, outside the car. Adds about 30 pounds to the car. "Perfect" alignment cannot be attained for all 3 height settings at the same time.
How did I get it?
A guy was selling it on Nasioc as "spare parts". Turned out only the wiring harness and hoses were cut upon uninstallation. $550 shipped from Canada. I figure $100 to ship it for an actual sales price of $450.
What does the system include?
Original instruction manual.
Compressor and mounting bracket.
Airtank with hose and tire chuck. Yeah... the ability to adjust the tires is gonna be nice.
Front height sensors and bracket to adapt mount the compressor in a WRX fenderwell. This should work for the Legacy too with minor mods.
Rear height sensors. They clamp right to the rear lateral links.
G-sensor. This is used to make sure the system doesn't try to self-level under braking or cornering.
Air dryer and disribution manifold. This is where the magic happens. They are mounted to a bracket that makes it a bolt-in affair for a WRX. Not sure yet how well it will fit the Legacy, I'm guessing it will be close, but not perfect.
Not one, but two ECUs. Orginal owner was having trouble with the self leveling. It was diagnosed as a bad ECU so it was replaced under warrenty. According to the owner that didn't help and the real problem was later found to be a bent rear transverse link causing the height sensor to be out of range. Yes, I'm taking a chance, but I rolling with it.
The strut units themselves. These are WRX fitment so all the "normal" stuff that needs to be done to fit WRX struts will need to be done. These came from a wagon, so the slotted holes are already done. Should just need to deal with the strut tops.
Compressor relay, dash switch w/current height indicator and main fuse. I'm hoping I can mod a OEM air suspension switch to work, but if not, no biggie.
Wiring harness, complete as far as I can tell. It's basically OEM quality and really impressive as far as aftermarket stuff goes. There are a few ends that were cut and need to be repaired. I'm not worried about this as it's something I am good at and I will need to lenthen it for the Legacy chassis anyways. There is also a disable switch and a calibrate button.
A bunch of the original hose. I won't likely be using that much of this stuff. It's just 1/4 inch DOT rated polytube. I'll feel better with new stuff.
I'm hoping to start the install over the weekend, but the entire thing will most likely take a few weeks.
What is Praxis?
Praxis is an experiment by Bridgestone/Firestone to enter the performance suspension market utilizing Firestones extensive experience with air springs. Even though the product is discontinued the website is still live. It can explain the basics better than I can: http://www.praxissystems.com/ In my research I discovered that most of the system is very similier to, and uses parts from, other Firestone "air-ride" systems.
The system can be considered a failure based on sales and an early retail retirement. In my opinion it failed because of price ($3500 new) and unreasonable expectations on the part of prospective customers.
Why am I installing it?
Because I believe it was a good effort to produce a versatile "all purpose" suspension that, IMHO, matches our Subaru's "go anywhere, do anything" pesonality. Particularly a turbo Subaru.
What are the pros?
Automatic, in-car, ride height AND spring rate adjustment. 12 position adjustable, inverted H&R struts. Automatic load leveling and corner weighting. Reduces side load on the strut. Reduces unsprung weight. It's really cool.
What are the cons?
Stuts are adjusted traditionally, outside the car. Adds about 30 pounds to the car. "Perfect" alignment cannot be attained for all 3 height settings at the same time.
How did I get it?
A guy was selling it on Nasioc as "spare parts". Turned out only the wiring harness and hoses were cut upon uninstallation. $550 shipped from Canada. I figure $100 to ship it for an actual sales price of $450.
What does the system include?
Original instruction manual.
Compressor and mounting bracket.
Airtank with hose and tire chuck. Yeah... the ability to adjust the tires is gonna be nice.
Front height sensors and bracket to adapt mount the compressor in a WRX fenderwell. This should work for the Legacy too with minor mods.
Rear height sensors. They clamp right to the rear lateral links.
G-sensor. This is used to make sure the system doesn't try to self-level under braking or cornering.
Air dryer and disribution manifold. This is where the magic happens. They are mounted to a bracket that makes it a bolt-in affair for a WRX. Not sure yet how well it will fit the Legacy, I'm guessing it will be close, but not perfect.
Not one, but two ECUs. Orginal owner was having trouble with the self leveling. It was diagnosed as a bad ECU so it was replaced under warrenty. According to the owner that didn't help and the real problem was later found to be a bent rear transverse link causing the height sensor to be out of range. Yes, I'm taking a chance, but I rolling with it.
The strut units themselves. These are WRX fitment so all the "normal" stuff that needs to be done to fit WRX struts will need to be done. These came from a wagon, so the slotted holes are already done. Should just need to deal with the strut tops.
Compressor relay, dash switch w/current height indicator and main fuse. I'm hoping I can mod a OEM air suspension switch to work, but if not, no biggie.
Wiring harness, complete as far as I can tell. It's basically OEM quality and really impressive as far as aftermarket stuff goes. There are a few ends that were cut and need to be repaired. I'm not worried about this as it's something I am good at and I will need to lenthen it for the Legacy chassis anyways. There is also a disable switch and a calibrate button.
A bunch of the original hose. I won't likely be using that much of this stuff. It's just 1/4 inch DOT rated polytube. I'll feel better with new stuff.
I'm hoping to start the install over the weekend, but the entire thing will most likely take a few weeks.
